I am experiencing that too. I’m having a sonogram of my heart on the 7th and I have to see my pulmonologist again. I had mild Covid for a week then a respite, and then it came back a week later with a lot of coughing, fever and fatigue. Now after finally testing negative I can barely get out of bed or do anything without having breathing problem and severe fatigue. Doctor says it just takes a long time to recover.